Pathogen update: Listeria monocytogenes

Recent advances regarding the human foodborne pathogen Listeria monocytogenes are discussed with specific emphasis on epidemiology, ecology and virulence. Recent routine surveillance and outbreak investigation studies indicate a shift in L. monocytogenes serotypes linked to listeriosis in some countries. There is growing evidence to show that L. monocytogenes isolates can be divided beyond the serotype level into at least two epidemiologically and genetically distinct subpopulations differentiated by biologically meaningful markers, including strains responsible for the majority of listeriosis cases and strains carrying virulence attenuating mutations in the key virulence gene inlA, which codes for internalin A.